1. Field of the Invention
The present invention relates to a hydraulic brake pressure control device of a load responsive type for controlling the hydraulic brake pressure which is supplied from a master cylinder to wheel cylinders for rear wheels in response to the load carried in a brake system for vehicles.
2. Discussion of the Related Art
Heretofore, in the field of automotive brake systems, there has been known a hydraulic brake pressure control device of a load-responsive type, wherein the hydraulic brake pressure supplied from a master cylinder is supplied to wheel cylinders for rear wheels as it is reduced in dependence upon the load carried. A housing of the device is attached to a vehicle body, and a lever which is in abutting engagement with a piston formed with a valve portion is pivotably carried on the housing. Between the rear wheel axle housing which supports the vehicle body by suspension mechanisms and a free end of the lever, there is further provided a spring member for urging the lever to contact the piston with the spring force which depends on the distance between the vehicle body and a rear axle housing.
In the brake hydraulic pressure control device as constructed above, however, the lever has a pivotal end in the direction toward the housing, in which end the lever is in abutting engagement with the piston formed with the valve portion. This configuration causes a problem to occur that when the vehicle runs on a bumpy road, the rear wheel axle housing is vibrated, and the lever is repetitively disengaged from, and engaged with, the piston thereby to generate an unpleasant or strange noise. In order that the lever is not disengaged from the piston upon the vibration of the rear axle housing, an attempt may be made that the spring member urging the lever toward the housing is changed to have a stronger spring force even when the vehicle carries a smaller load. However, such an attempt disadvantageously causes the hydraulic brake pressure to increase, so that the freedom of allocating the hydraulic brake pressures to front and rear wheels is diminished.